Assionob to the bubber service labo



Patented June 5, 1928.

UNITED STATES PATENT OFFICE.

WILLIAM B. TEB. HORST, OI AKRON, OHIO, ASSIGNOR TO THE RUBBER SERVICE LABO- RATOBIES COMPANY, OF AKRON,

OHIO, A CORPORATION OI OHIO.

PROCESS OF MANUFACTURING VULCANIZED RUBBER.

Ho Drawing. Application filed lay 6,

This invention is directed to the art of manufacturing a vulcanized rubber product by employing tetra-substituted-derivatives f guanidine as accelerators of the vulcanization process. The mode of operatin the in vention will be readily understood from the following specification and examples wherein the invention is fully set forth and described.

Guanidine has the formula- C=NH Nrh

and is known as the amidine of carbamic acid. The five hydrogen atoms shown who present in guanidine are replaceable by various atoms or radicals to produce a mono, di, tri, tetra, or penta substituted guanidine, depending upon the number of hydrogen atoms so replaced.

and the like. Groups of an alkaloidal ty such as piperidyl, pyrollidyl, and the li e have also been su stituted for hydrogen atoms in guanidine, to obtain tetra-substituted derivatives of the type claimed.

An example of one such compound is dipiperidyl-guanidine wherein four of the hydrogen atoms of guanidine have been replaced in the manner shown in the following formula This compound was manufactured preferably by passing vapors of cyanogen chloand substitut aryl groups, such as 1927. Serial No. 189,463.

The tetra substituted guanidines of the type hereinafter set forth and which are manufactured preferably by the process described in detail comprise a class of com- I pounds which may be represented by the 26 formula N RAB! C=NH \N RI Ra,

where;R,, R gi'wd R, indicate alkyl, aryl 30 or cyclic groups of hydrocarbon or substitute hydrocarbon characteristics which may be the same or may be all different groupings. Such groups may comprise alkyl groups such as the methyl, ethyl, propyl, butyl group and the like, or aryl groups such as the phenyl, tolyl, and xylyl groups produced there rom, a container in which the reaction was carried out was connected with a reflux condenser. The flow of cyanoe5 gen chloride was continued for a period of time suificientto produce the hydrochloride of the desired guanidine derivative.

The reaction product so obtained was taken up with water, the water extract was filtered and the filtrate was then treated-with an alkaline solution, preferabl caustic soda, to obtain the free guanidine ase. .The alkali should be added preferably in an amount suificient to react faintly alkaline to an indicator such as Clayton yellow. The guanidine compound formed was redissolved in hydrochloric acid and the acid neutralized by treatment with a caustic solution as be fore. The di-piperidyl-guanidine so ob tained Was then washed until substantially free from soluble salts and Was then dried in any suitable manner, preferably in vacuo. The product is then ready for use as an accelerator of the rubber vulcanization process but can be further purified, if desired, by treatment with any suitable material, such as benzol.

Another reaction product which is a tetra substituted guanidine of the type set forth herein was obtained by reacting ethyl-otoluidine with cyanogen chloride in the manner as described. The reaction product obtained possessed the following structure:

In a like manner, phenyl-methyl-p-tolylguanidine "has been obtained by reacting cyanogen chloride upon a mixture ofequr molecular proportions of aniline and methyl p-toluidine. In a similar manner other tetra substituted. guanidines have been manufacture'dby reacting cyanogen chlorlde substan- 't-ial'ly inthe manner as described with the desired. amino compound, mixtures of amino compounds or a derivative or derivatives thereof.

The following is an example illustrative of the use of a tetra substituted guanidine as an accelerator in the rubber vulcanization process. A. rubber mix comprising 100 parts of pale crepe rubber, parts of zinc oxide, I 3.5 par-ts of sulphur, and 0.5 parts of di-piperidyl-guanidine,

I Modulus of elasticity Tensile 5 3 at elongation of- Ulti- Time of mm of break mate heating heat 7 in elongamg 300% 500% 700% lbs/in2 15 min 237 111 186 534 2218 945% -30'1m'n 287 174 395 1760 3830 870% Another example illustrative of tlieaise of the new accelerating compounds herein disclosed is the followmg rubber mix which comprises a typical tread stock. Such a mix comprises 30.5 parts smoked sheet rubber,

20.0 parts No. 2 amber rubber,

25.0 parts carbon black,

2.0 parts sulphur,

1J0 part a blended vegetable and mineral oil 1.0 part stearic acid,

3.5 parts mineral rubber,

11.0 parts zinc oxide,

1.0 part di-piperidyl-guanidine.

The rubber mix was then vulcanized by heating for approximately sixty minutes in a press ma inta'ined at a temperature of 287 F. (a temperature given by forty pounds of steam pressure per square inch). The vulcanized product was found upon testing to possess a modulus of elasticity at 300% elongation of 1915 pounds per square inch, at 500% elongation of 1115 pounds per square inch, a tensile strength at brealrof 4590 pounds per square inch and an ulti mate elongation of 515%.

A hard rubber compound of high quality was obtained by heating for about two hours and forty-five minutes in a press maintained at 287 F, a rubber mix comprising:

Other tetra substituted guanidine compounds have also been employed as vulcanization accelerators. Thus, in a rubber 'miX comprising 100 parts of pale crepe rubber, 3.5 parts of sulphur, and 5 parts of zinc oxide,

1 have successfully used as an accelerator 0.5 arts of a tetra substituted guanidine resulting from the reaction of ethyl-o-toluidine, or a mixture of aniline and methyl-ptoluidine and other like compounds in the manner as described with cyanogen chloride.

The examples hereinbefore given are to p be understood as illustrative only and not at all limitative of the scope of my invention. Other compounding ingredients and other proportions of these ingredients and of the accelerator set forth than were used in the various examples given may be employed to produce rubber compounds of a desired type. Moreover other means of manufacturing the particular accelerators claimed may be employed, if desired. The invention is to be considered as limited only by the following claims wherein I intend to claim loo my invention as broadly as is permissible in view of the prior art.

What I claim is:

1. The process of treating rubber or similar substances which comprises combining with the rubber compound a vulcanizing agent and a tetra substituted guanidine accelerator.

2. The process 01' manufacturing vulcanized rubber which comprises combining with the rubber compound a vulcanizing agent and a tetra substituted guanidine accelerator, such accelerator possessing the formula NRIRI o =Nn Nmm where R R R and R, represent organic radicals.

3. The process of manufacturing vulcanized rubber which comprises combining with the rubber compound a vulcanizing agent and a tetra substituted guanidine accelerator, said accelerator possessing the formula where R and R, represent organic radicals and R and R represent groups possessing a ring structure.

4. The process of manufacturing vulcanized rubber which comprises combining with the rubber compound a vulcanizing agent and a tetra substituted guanidine accelerator, said accelerator possessing the formula where X and IX, represent groupings of an alkaloidal type.

5. The process of manufacturing vulcanized rubber which comprises combining with the rubber compounds at vulcanizing agent and a tetra substituted guanidine accelerator, said accelerator possessing the formula 24 42M. Xl

where X and X represent piperidyl groupings.

6. The process of manufacturing vulcanized rubber which comprises heating a mixture of rubber and sulphur with a relatively small proportion of di-piperidyl-guanidine.

7. As a new product, a vulcanized rubber derived from rubber, a vulcanizing agent and avulcanizing ingredient comprising a tetra-substituted-guanidine accelerator.

8. As a new product, a vulcanized rubber derived from rubber, a vulcanizing agent and a vulcanizing ingredient comprising a tetra-substituted-guanidine accelerator, said accelerator possessing the formula ar I NR|Ra where R R R and R represent organic radicals.

9. As a new product, a vulcanized rubber derived from rubber, a vulcanizing agent and a vulcanizing ingredient comprising a tetra-substituted-guanidine accelerator said accelerator possessing the formula where R and R represent organic radicals and R and R represent groups possessing a ring structure.

10. As a new product, a vulcanized rubber derived from rubber, a vulcanizing agent and a vulcanizing ingredient comprising a tetra-substituted-guanidine accelerator, said accelerator possessing the formula where X and X represent piperidyl group ings.

12. A rubber product obtained by heating a mixture of rubber and sulphur in the presence of a small proportion of an accelerator comprising di-piperidyLguanidine.

In testimony whereof I aifix my signature.

WILLIAM P. TER HORST. 

